Behavioural barriers to gene flow can play a key role in speciation and hybridisation. Birdsong is well-known for its potential contribution to such behavioural barriers as it may affect gene flow through an effect on territorial and mating success across population boundaries. Conspecific recognition and heterospecific discrimination of acoustic variation can prevent or limit hybridization in areas where closely related species meet. Here we tested the impact of song differences on territorial response levels between two adjacent Henicorhina wood-wren species along an elevational gradient in Colombia. In an earlier study, playback results had revealed an asymmetric response pattern, with low-elevation H. leucophrys bangsi responding strongly to any conspecific or heterospecific song variant, whereas high-elevation H. anachoreta birds discriminated, responding more strongly to their own songs than to those of bangsi. However, in that study we could not exclude a role for relative familiarity to the song stimuli. In the current study we confirm the asymmetric response pattern with song stimuli recorded close to and on both sides of the distinct acoustic boundary. Furthermore, we also show a previously unnoticed divergence in singing style between these two wood-wren species, which may contribute to an acoustically guided barrier to hybridization in this secondary contact zone.
Hybridization and speciation. —
J. Evol. Biol.26:
Female, but not male, tropical sparrows respond more strongly to the local song dialect: implications for population divergence. —
Asymmetric response patterns to subspecies-specific song differences in allopatry and parapatry in the grey-breasted wood-wren. —
Evolutionary implications of the interaction between animal signals and the environment. — In:
Animal signals. Signalling and signal design in animal communications (
EspmarkY.AmundsenT.RosenqvistG. eds). The Royal Norwegian Society of Sciences & LettersTrondheim p.
Frequency matching, overlapping and movement behaviour in diurnal countersinging interactions of black-capped chickadees. —
KirschelA.N.G.SlabbekoornH.BlumsteinD.T.CohenR.E.de KortS.R.BuermannW.SmithT.B. (2011).
Testing alternative hypotheses for evolutionary diversification in an African songbird: rainforest refugia versus ecological gradients. —